Sealing arrangement for fluid flow engines

Abstract

A sealing arrangement between the shaft and housing of a fluid flow engine with a blocking gas space limited by piston rings; the blocking gas pressure is controlled by changing the effective cross section of venting bores and therewith is matched to the gas pressure to be sealed off; the change of the cross section of the venting bores is thereby automatically realized by axial displacement of the corresponding piston ring as a function of the gas, respectively, blocking gas pressure acting on the same. An axial wear at the piston ring and at the groove flank, which is present during the running-in period, is avoided subsequent thereto as a result of the decrease of the blocking gas pressure.

I claim: 
     
       1. A sealing arrangement for fluid flow engines having two seal means arranged adjacent one another, at least one of said seal means being constructed as piston ring seal, the space formed between the two seal means being operable to be filled with a blocking gas and to be vented by way of vent bore means with adjustable cross section, characterized in that the orifice of the vent bore means in the blocking gas space is operable to be substantially covered off by the piston ring and in that the cross section of the vent bore means effective for the relief of the blocking gas space can be changed by axial movement of the piston ring. 
     
     
       2. A sealing arrangement according to claim 1 in which a groove flank in the part accommodating the piston ring limits axial movement thereof, characterized in that the axial movement of the piston ring for changing said cross section is made possible by wear at abutment surfaces of the piston ring and of the groove flank and in that the axial movement is terminated by pressure equalization on both sides of the piston ring which will establish itself. 
     
     
       3. A sealing arrangement according to claim 1, wherein the fluid flow engine includes a shaft, bearing means supporting said shaft in a housing on one side of one of said seal means, said shaft being exposed to hot gases on the other side of the other seal means, and said seal means together with the pressure in the gas blocking space preventing the penetration of the hot gases into said bearing means. 
     
     
       4. A sealing arrangement according to claim 3, wherein said piston ring is accommodated in a groove in said shaft, the axial movement of said piston ring in said groove in the direction toward said hot gases being limited by a groove flank, and the extent of axial movement of said piston ring in said last-mentioned direction being automatically limited by wear between said piston ring and said groove flank. 
     
     
       5. A sealing arrangement according to claim 4, wherein the wear between said piston ring and said groove flank is terminated when the opening of vent bore means as a result of such wear has reached a predetermined cross section. 
     
     
       6. A sealing arrangemet according to claim 5, wherein both seal means are constructed as piston rings. 
     
     
       7. A sealing arrangement according to claim 1, wherein both seal means are constructed as piston rings.